Tensioning weft material in a loom for weaving



Feb. 5, 1963 I E. PFARRWALLER 7 3,076,483

wsnsroumc WEFT MATERIAL IN A LOOM FOR WEAVING Filed June 25. 1960 2 Sheets-Sheet 1 Feb. 5, 1963 E. PFARl RWALLER 3 TENSIONING WEFT MATERIAL IN A LOOM FOR wmvmc Filed June 25; 1960 2 Sheets-Sheet 2 United rat 3,076,483 TENSIONING WEFT MATERIAL IN A LOOM FOR WEAVING Erwin Pfai'rwaller, Winterthnr, Switzerland, assignor to Sulzcr Freres, S.A., Winterthur, Switzerland, 21 corporation of Switzerland Filed June 23, 1960, Ser. No. 38,237 Claims priority, application Switzerland June 26, 1959 (Claims. '(Cl.139-=-126) The present invention rel-ates to a method and means fortensioning weft material to be inserted into a shed formed by warp threads'in a weaving machine wherein the weft material is pulled from spools placed outside of the shed, the weft'materi-al moving through two stationary eyes and a movable intermediate eye for pulling the weftm-aterial away from the stationary eyes for tensioning the weft material and for moving the movable eye towards the stationary eyes for slackening the material. The inventionis particularly concerned with the timing of the "movement of the movable eye relative to the starting of the weft thread inserting operation. The invention also relates to a device for carrying out the method.

In the method according to the invention, movement of the movableeye orguide means for the weft material towards animaginary line interconnecting the stationary eyes or guide means for slackening the weft material begins prior to starting the weft inserting device on its way through the shed.

The device according to the invention includes conventional weft material tensioning means as shown, for example, in Patent No. 2,817,367. However, the drive means of thi tensioning means includes timing means for initiating movement of the movable thread guide for slackening the weft material prior to starting of the weft inserting device on its travel through the shed. In the conventional thread tensioning arrangements the eye for guiding the thread is located at the end of a lever. If this lever is moved for slackening the weft material prior to starting the weft inserting device, the thread forms loops or bends on oneor on both sides of the lever which may be thrown around the free end of the lever, i.e. will be made fast thereon, so that the pull exerted by the started weft insertion device will tear and break the weft material. To avoid this, the present invention provides placing the eye or guide means at a'distance from the free end of the lever on which it is mounted. The portion of the lever extending beyond the eye prevents slinging of the loose portion of the weft material around the lever.

, The novel features which are considered characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, and additional objects and advantages thereof will best be understood from the following description of embodiments thereof when "read in connection with the accompanying drawing, wherein:

FIG. 1 is a diagrammatic illustration of parts of a weaving machine including the parts involved in the method according to the invention.

FfG. 1a is a diagrammatic illustration of the common drive means for the essential parts of the arrangement according to the invention.

FIG. 1b is a largescale illustration of a detail of the mechanism shown in FIGS. 1 and In.

FIG. 2 is a diagram illustrating the timing of the movement of a movable weft thread guide according to the invention.

M FIG. 3 shows a movable weft material guide interposed between and spaced from two stationary guides in two different operating positions and shows the configu- 3,h?fi,d83 Patented Feb. 5, 1963 ration of the guided weft material if the movement of the movable guide is timed according to the invention.

FIG. 4 is a large scale illustration of a weft thread guide and of a portion of the element on which the guide is mounted.

Referring more particularly to the drawing, numeral 11 designates weft material which may be a thread or a wire and which is pulled from a stationary bobbin 12.. The material passes through an eye 13 mounted on a stationary part of the weaving machine, through a brake 14 and thereupon through a stationary guide or eye 15. The weft material travels from the latter through 'a thread guide or eye 17 provided at the free end of a carrier or tensioning lever 18 and thereupon through a stationary guide or eye 16. The lever 18 which is swingable around a pin 22 is actuated by a cam which is fast on a shaft 21. Instead of actuating the lever '18 directly by'the cam 19 on the shaft 21, the lever may be connected to a cam follower device 47, 48 by means of a link 49, as shown in FIG. la. The shaft 21 is operatively connected to and rotated in the direction of the arrow 59 synchronously with the main drive, not shown, of the weaving machine, for example, by means of a chain 46 extending around a sprocket wheel 45 on the shaft 21.

From the eye 16 the weft material passes through a pullback device 23 which is opened by an opener 24, for example as shown in Patent No. 2,589,429. The pullback device is reciprooated by a groove cam 55 to which it is operatively connected by means of a lever 56 and a connecting rod 57.

The end of the weft material is gripped by a clamp 25 on a shuttle 26. The latter rests on a nose 27 of a shuttle picker 28 which may be fast on a torsion spring 28a as shown, for example, in Patent No. 2,160,338. The torsion spring is tensioned by the loom drive in the conventional manner. The shuttle picker 28 is released by disconnecting a latch element 36 there-from. This ele ment is actuated by a cam 51 which is fast on the shaft 21 and followed by a roller '52 at one end of a rod 53 whose second end is pivoted to the latch element St).

If weft inserting needles are used instead of a gripper shuttel, the needles are directly operatively connected to the drive of the weaving machine.

In the illustrated position of the device the shuttle 26 is ready to be picked through the shed 29 which is open. A thread cutter 31 which is adjacent to the shed is in open position permitting passage of the shuttle. A thread clamp 32 which is for the purpose of transporting an inserted weft thread from the picking line to the beat-up position is in rest position, i.e. away from the shuttle path or picking line.

The lever 18 is in its uppermost position and has pulled the weft thread 11 away from the guides 15 and 16. The pulled-up portion of the weft thread is taken up when the weft inserting device moves through the shed. In the initial position, there is a rather sharp diversion of the thread material at the eyes 15, 16 and 17. The bends of the thread produced by the thread tensioner 17, 18 begin to be reduced by lowering the lever 18 at the latest when the shuttle 26 is started on its way through the shed. When the length of weft material between the eyes 15 and 16 is taken up by the weft inserting operation and the weft material follows a straight line between the eyes and 16, additional weft material must be pulled off the bobbin 12 whereby the thread tension is considerably increased compared with the rather low tension effected by the operation of the movable thread guide 17.

In the conventional arrangements, lowering of the lever 18 usually begins simultaneously with starting of the shuttle. This leaves the material between the eyes Lu, 1'7 and 1d at considerable tension; in addition, there are 3 sharp bends at the eyes. lhese circumstances are likely to cause thread breakages. An exact coordination of the shortening of the thread bend between the eyes lie" and lo and the movement of the shuttle 26 through the shed 29 by correctly timing the movement of the lever 2' is very dillicult.

has been found that thread breakages can be reduced or entirely avoided by temporarily slackening tire thread between the eyes 1-5 and 16, if re-tensioning of the thread is cfrected at a time when the bends at 15, 17 and 1e are not too sharp. Sudden stretching of the thread is reduced by the inherent elasticity of the weft material, if suflicient thread length is available. Reduced diversion of the thread facilitates absorption of the jerk in the thread portion which is distant from the shuttle. Thick and still material is subiected to bending stresses at the points of diversion which stresses are smaller if the angle of diversion is not acute. Retardation of the collapse of the bend between the guides 15, 17 and or LOO great acceleration of the shuttle may cause tensions in the weft material which may result in thread breakages. This is avoided by me method and device according to the invention.

In the diagram FIG. 2 the abscissa represents the angular movement of the main shaft of the weaving machine between and W". The ordinates represents the stroke h of the movable thread guide W. The shuttle 26 is started on its way through the shed at the angular position A. Downward movement of the lever lb is initiated, according to the invention, at the angular position 12, 0, or d" of the main shaft of the loom, i.e. before the starting of the shuttle, so that there is sufficient slack weft material available for the shuttle picking operation. he extent of advance of lowering the lever 1% depends on the relation between the acceleration of the shuttle and the speed of rotation of the shaft 21. The greater the acceleration the earlier the lever 12 must be lowered so that the thread material 11 is loose during the downward movement of the lever 18.

it may be of advantage to begin and continue lowering of the lever 28 in such manner that the weft material between the guides 15 and 16 is relieved of tension without producing loose portions of the material. in this way, g erks are avoided when the lever approaches its lowermost position and weft material must be pulled from the spool 12. By suitably shaping the cam 19, the weft material can be gradually accelerated until the moment when the material is pulled directly from the spool 32 so that stresses in the weft material are reduced and breakages are avoided.

As long as the eye 17 is in the uppermost position i, the weft material llI; is under a slight tension between the eyes 1.5, R7 and 16, as shown by a solid line in HQ. 3. if lowering of the lever 18 is begun at the angular position c of the main loom shaft and the shuttle 26 is started at the angular position A, no weft material is pulled through the eye in during the period of time between the positions 0 and A of the loom shaft. The eye 17 has moved to the position ll when the shuttle is started on its way through the shed. At this moment the length of the weft material between the guides and 1i; i as not been changed. Due to the acceler tion of the lever 13 and the inertia of the thread material ll, bends and are formed at either side of the guide as shown by a dash-dot line in 3, or a bend tis formed only on one side of the eye 17 as indiated oy a dotted line in PEG. 3. The bends and 4- are approxima ely half as great as the bend d2. Since the bends can freely move, there is a danger that, for example, the bend ES -nay swing around the lever la} an become entas led in the bend 41, or that the weft material slings around the of the lever If new, when the eye 17 is in the position ll and the shuttle is started, weft material puller: "ire-ugh the eye 36, the sling extending around the end of the lever 7.8 is tightened the thread ii is broken.

l- To avoid situations as described in the paragraph next above, be lever 18 is provided with a head extent ng by the length a beyond the eye 17. With this extension the lever, the bends 411, ll or 42 abut against the lever but cannot swing therearound. After starting or" the shuttle, the bends it) to 42 cannot be enlarged, because the thread 11 is pulled though the e 'e 16 simultaneously with the lowering of the eye 1'7. The length a of the extension 2-3 of the lever 13 beyond the eye 17 is preferably at least one half of the length of the paths (ill) traveled by the eye i7 between initiation of the movement thereof towards an imaginary line connecting the eyes 15 and 3.6 and the moment of starting the weft inserting device.

In order to be in position to change the extent of advance of the beginning of the lowering of the lever 18 relative to the moment at which the shuttle 26' is started, the cam 19 may be made exchangeable or adjustable with respect to its angular position on the shaft 21. This is of importance when the weaving machine is prepared for producing a different weave. A device 65 for changing the angular position of the cam 19 is shown in FIG. 1b.

In cases where the movable eye 17 on the lever 18 moves towards the line interconnecting the stationary eyes 15, 1.6 at or after the beginning of the weft inserting operation, the provision of a head 43 extending by the length a or more beyond the eye 17 will be advantageous when the velocity of this downward moving is greater than the velocity of inserting the weft thread into the shed.

In FIG. 1a the downward moving of the lever 48 begins when the roller 47 reaches the radius 61 on the cam 19. On the cam 51 is marked a radius 62 corresponding to the radius 61 on the cam 19. However, when the roller 52 reaches the radius 62 the latch element 30 is not raised. This happens only when the roller 52 reaches the radius 63 corresponding to the top 64- of the cam 51. At this moment the element 30 is raised and the weft inserting operation begins.

I claim:

1. The method of tensioning the weft material in a loom for weaving which material is pulled from spools placed outside of the shed formed by warp threads and which material moves consecutively through a stationary eye, through a movable eye, and through a stationary eye onto a device for inserting the weft material into the shed, the movable eye being placed outside of an imaginary line connecting the two stationary eyes and being moved towards said line for slackening the weft material and being moved away from said line for tensioning the weft material, the method including the steps of beginning to move the movable eye towards the line interconnecting the stationary eyes for initially releasing weft material before the beginning of the weft inserting operation, and thereupon continuing movement of the movable eye towards the line interconnecting the stationary eyes for releasing additional weft material while the weft inserting operation continues.

2. The method defined in claim 1 wherein the period of time between the beginning of the movement of the movable eye towards the line interconnecting the statronary eyes and the beginning of the Weft inserting operation is greater initial acceleration of the weft inserting device and is smaller at smaller initial acceleration of the weft inserting device.

3. In a loom for weaving of the type wherein weft material, which is inserted into a shed formed by warp threads, is pulled from spools located outside of the shed: two spaced stationary guide means for guiding the Weft material, a movable guide means placed outside of an imaginary line connecting said stationary guide means, a weft inserting device, the weft material extending consecutively through one of said stationary guide means, said movable guide means, and the second stationary guide means to said weft inserting device, means for moving said movable guide means towards said line interconnecting said two stationary guide means for slackening the weft material and for moving said movable guide means away from said line for tensioning the warp material, means for starting said inserting device on its way through the shed formed by warp threads, and drive means common to said means for moving said movable guide means and to said starting means, said drive means including timing means for initiating movement of said movable guide means towards said imaginary line and initially slackening the weft material prior to starting said inserting device, and for continuing said movement of said movable guide means while said inserting device inserts the weft thread into the shed.

4. In a loom for weaving of the type wherein weft material, which is inserted into a shed formed by warp threads, is pulled from spools located outside of the shed: two spaced stationary guide means for guiding the weft material, a movable guide means placed outside of an imaginary line connecting said stationary guide means, a weft inserting device, the weft material extending consecutively through one of said stationary guide means, said movable guide means, and the second stationary guide means to said weft inserting device, means for moving said movable guide means towards said line interconnecting said two stationary guide means for slackening the weft material and for moving said movable guide means away from said line for tensioning the warp material, means for starting said inserting device on its way through the shed formed by warp threads, and drive means common to said means for moving said movable guide means and to said starting means, said drive means including timing means for advancing movement of said guide means towards said imaginary line relative to said starting means for initially slackening the weft material, said movable guide means being in the form of a lever having an aperture forming an eye for guiding the weft material, said lever having an end portion extending beyond said aperture.

5. In a loom for weaving as defined in claim 4 and wherein said timing means is constructed and arranged so as to move said movable guide means towards said imaginary line prior to starting said inserting device, said eye being placed on said lever at a distance from the free end of the lever which distance is equal to at least one half of the path traveled by said eye between the moment of initiation of the movement thereof towards said imaginary line and the moment of starting said weft inserting device.

References Cited in the file of this patent UNITED STATES PATENTS 1,515,838 Clark Nov. 18, 1924 1,900,545 Darienzo Mar. 7, 1933 1,964,079 Pool June 26, 1934 2,089,620 Rossmann Aug. 10, 1937 2,407,773 Fletcher Sept. 17, 1946 FOREIGN PATENTS 575,548 Great Britain Feb. 22, 1946 575,804 Great Britain Mar. 6, 1946 478,556 Italy Feb, 25, 1953 

1. THE METHOD OF TENSIONING THE WEFT MATERIAL IN A LOOM FOR WEAVING WHICH MATERIAL IS PULLED FROM SPOOLS PLACED OUTSIDE OF THE SHED FORMED BY WARP THREADS AND WHICH MATERIAL MOVES CONSECUTIVELY THROUGH A STATIONARY EYE, THROUGH A MOVABLE EYE, AND THROUGH A STATIONARY EYE ONTO A DEVICE FOR INSERTING THE WEFT MATERIAL INTO THE SHED, THE MOVABLE EYE BEING PLACED OUTSIDE OF AN IMAGINARY LINE CONNECTING THE TWO STATIONARY EYES AND BEING MOVED TOWARDS SAID LINE FOR SLACKENING THE WEFT MATERIAL AND BEING MOVED AWAY FROM SAID LINE FOR TENSIONING THE WEFT MATERIAL, THE METHOD INCLUDING THE STEPS OF BEGINNING TO MOVE THE MOVABLE EYE TOWARDS THE LINE INTERCONNECTING THE STATIONARY EYES FOR INITIALLY RELEASING WEFT MATERIAL BEFORE THE BEGINNING OF THE WEFT INSERTING OPERATION, AND THEREUPON CONTINUING MOVEMENT OF THE MOVABLE EYE TOWARDS THE LINE INTERCONNECTING THE STATIONARY EYES FOR RELEASING ADDITIONAL WEFT MATERIAL WHILE THE WEFT INSERTING OPERATION CONTINUES. 